Chap. V. A N T I EN T M E T A P H Y S I C S. 39E 



That the iirfl: kind of compofition is not only pofhble, but does 

 adlually cxift in this Earth, cannot be denied. It is in this way that 

 a ftone in a fling is moved, which is an example given by Sir Ifaac*. 

 The ftone is projcdcd by the adion of the hand, and it is retained 

 from going forward by the firing which the flinger holds in his 

 hand. It is therefore plainly adled upon by two Bodies in oifTerent 

 dircdions. And, as the adtion of the hand, always forcing it on, 

 does, by thefe repeated impulfcs, give it a great progrefl!ivc force, 

 when the ftring that holds it is let go, it flies to a great diftance. 

 There is alfo a compounded Motion of the fccond kind, when the 

 Body is aded upon, partly by Mind and partly by Body. Of this 

 kind of compofition of Motion we have alfo an example in the cafe 

 of an Animal which wants to move forward, but, by the adion of 

 Body upon him, is moved in a curve. Such is the Motion of a 

 horfe that is lounged^ who would go on in a flralght line, but, by the 

 adion of a rope upon him, rs drawn into a curve. 



Thnt the compofition, if there he any, of the Planetary Mcj— 

 tion, is not of either of thcfe two kinds, I hope I have con- 

 vinced my readers, unlcfs we were to fuppofe, in the celeftial 

 fpaces, Bodies, of the exlftencc of which there is neither proof 

 nor the leafl: probability. . And, particularly, there is no phi- 

 lofopher, as far as I know, that has imagined that there is any fuch 

 thing as a real ftring, by which the planets are drawn into their or- 

 bits round their centre, like to that by which the horfe or the ftone, 

 in the examples given, is drawn into a ring. For, though Sir Ifaac has 

 ufed the example of the ftone in the fling, by way of illuftration of 

 his dodrine of Projedion and Gravitation, yet, I am perfuaded, he 

 did not believe that there was any String, or Body of any kind, be- 

 twixt the Planet and the Centre, by which it is drawn to its centre. 

 If, therefore, the Planetary Motion is at all compounded, it muft be 

 fo in the third way I mentioned, that is, by the operation of Mind 

 only, and not one Mind but two Minds ; one of which carries on 



the 



• Principiny defin. 5. 



